1. Field of the Invention
This invention pertains to surgical instruments generally and, more particularly, to a manually operated curvilinear surgical punch for trimming meniscal tissue and achieving a smooth cut surface thereupon.
2. Description of the Background Art
The advent of arthroscopic surgery greatly simplified surgical procedures performed upon the knee. Arthroscopy enabled surgery to be performed inside the knee, using a minor-invasive technique involving operating through small holes cut into the knee. Previously, the entire knee joint had to be surgically opened and invaded, thereby increasing the potential for infection, and requiring the patient to endure a long convalescence.
A particularly common facet of arthroscopic surgery involves operating upon the meniscal tissue inside the knee. The meniscus is a fibrous, cartilaginous, tissue, prevalent in the knee joint, which serves a shock absorption function inside the knee, thereby continuously protecting the knee joint from damage. As a result of acute injury or continuous wear upon the meniscus while performing its shock absorption function, the meniscus often degrades, becoming ragged and torn at the edges in the process. When the meniscus degrades, the ragged edges can abrade inside the knee joint, causing irritation, and necessitating surgery to remove the ragged edges. A goal in designing instruments for meniscal tissue surgery has been to achieve a design which cleanly debrides the degenerative meniscal tissue to a smooth, curved meniscal remnant. A meniscal remnant with a smooth surface eliminates abrasion within the knee joint, thereby eliminating irritation caused to the patient, following surgery.
Heretofore, a variety of surgical instruments have been developed which trim meniscal tissue to varying degrees of smoothness. These instruments have been of three primary types: (i) manually operated cutting instruments, including punch-type instruments; (ii) motorized trimming instruments; and (iii) laser surgery instruments. The punch-type instruments devised to date have suffered from inherent limitations in achieving sharp, clean, smooth, meniscal remnants and also require numerous passes to achieve a reasonably smooth meniscal remnant. The motorized instruments produce smooth meniscal remnants, but also require a multitude of passes to achieve this result. The laser instruments provide a smooth surface with a minimal amount of surgical passes; however, their high operating expense has proven to be a negative factor in their application to meniscal surgery. Therefore, there still exists a need for an instrument which can achieve an exceptionally smooth meniscal remnant, while requiring as few passes as possible, with the least expense, to achieve this favorable result.
The present invention achieves superior results in obtaining smooth meniscal remnants over previous instruments by employing a curvilinear cutting surface having a long, sweeping curve length. This long curve length allows the surgeon to achieve a smooth meniscal remnant in one or two passes with the instrument, thereby reducing the time required for meniscal trim surgery. Previous meniscal surgery instruments do not possess curvilinear cutting surfaces equivalent to the present invention disclosed herein.
For example, U.S. Pat. No. 2,994,321 issued to Tischler on Aug. 1, 1961, discloses a biopsy punch for taking tissue samples. This instrument has a set of jaws comprised of a top and a bottom cutting surface which are closeable upon each other. The cutting surfaces are tapered towards their ends in a "boat bottom" shape. U.S. Pat. No. 3,391,690 issued to Armao on Jul. 9, 1968, discloses a biopsy punch having a set of jaws comprised of a pair of closeable cutting surfaces. The cutting surfaces may be of a variety of shapes, including elliptical shapes.
A trade brochure published by Acufex Microsurgical Inc., discloses several manually operated instruments which are applicable to meniscal surgery procedures. One such instrument is a hooked rotary scissors with a slightly curved cutting surface. This instrument can be manufactured in left and right configurations for operating upon the left and right meniscus, respectively. The Acufex publication also discloses a scissor punch which can be manufactured in straight and upcurving configurations. In addition, a variety of single-bladed "meniscectomy" knives having a plurality of shapes are shown. A trade brochure published by Arthrotek discloses a variety of elliptical meniscal punches which are designed specifically for achieving smoother meniscal remnants. The width of the elliptical portions of these punches is a maximum of 3.4 mm.
U.S. Pat. No. 4,662,371 issued to Whipple et al. on May 5, 1987, discloses a surgical instrument used for meniscal surgery comprised of an elliptical punch having a top surface which closes upon a bottom surface. This instrument also has a suction means for removing severed meniscal tissue from the knee joint. U.S. Pat. No. 4,971,067 issued to Bolduc et al. on Nov. 20, 1990, as well as U.S. Pat. No. 4,986,825 issued to Bays et al. on Jan. 22, 1991, both disclose surgical instruments having U-shaped cutting surfaces. U.S. Pat. No. 2,930,376 issued to Rathmann on Mar. 29, 1960, discloses a surgical instrument having a triangular cutting surface. U.S. Pat. No. 2,192,699 issued to Storz on Mar. 5, 1940, discloses a surgical instrument having closeable jaws, the jaws having convex surfaces for removing circular sections of tissue. U.S. Pat. No. 3,835,860 issued to Garretson on Sep. 17, 1974, discloses a surgical bone punch for cutting and shaping bone or cartilaginous tissue. U.S. Pat. No. 4,990,148 issued to Worrick, III et al. on Feb. 5, 1991, discloses a rongeur which can be used for removing tissue from the vertebrae or knee. U.S. Pat. No. 2,541,246 issued to Held on Feb. 13, 1951, discloses a surgical instrument for cutting muscle tissue. U.S. Pat. No. 4,545,374 issued to Jacobson, discloses a surgical instrument for performing a lumbar diskectomy. U.S. Pat. No. 4,976,269 issued to Mehl, on Dec. 11, 1990, discloses a tissue needle for extracting a biopsy sample. U.S. Pat. No. 4,712,545 issued to Honkanen on Dec. 15, 1987, discloses a surgical instrument having a pair of cutting jaws adapted for removing tissue. U.S. Pat. No. D-289,437 issued to Honkanen on Apr. 21, 1987, discloses a design for a combined handle and shank for a surgical instrument.
The foregoing patents disclose a variety of surgical instruments which are designed for removing meniscal, or other tissue. Several of the previous designs also disclose surgical instruments having elliptically curved cutting surfaces, but none disclose the long, sweeping, curvilinear cutting surface of the present invention. The configuration of the curvilinear surgical punch disclosed herein provides for smoother meniscal trims, with fewer passes, than previous designs. The smoothness of the resulting meniscal remnant causes less irritation to the patient and by employing the present invention, fewer passes are required to achieve a smooth meniscal remnant, which reduces the time required for meniscal surgery.
The foregoing patents and publications reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents or publications, teach or render obvious, singly or when considered in combination, applicant's claimed invention.